A discussion about the limitations of the Eurocode’s high-speed load model for railway bridges

High-speed railway bridges are subjected to normative limitations concerning maximum permissible deck accelerations.For the design of these structures,the European norm EN 1991-2 introduces the high-speed load model(HSLM)—a set of point loads intended to include the effects of existing high-speed trains.Yet,the evolution of current trains and the recent development of new load models motivate a discussion regarding the limits of validity of the HSLM.For this study,a large number of randomly generated load models of articulated,conventional,and regular trains are tested and compared with the envelope of HSLM effects.For each type of train,two sets of 100,000 load models are considered:one abiding by the limits of the EN 1991-2 and another considering wider limits.This comparison is achieved using both a bridge-independent metric(train signatures)and dynamic analyses on a case study bridge(the Canelas bridge of the Portuguese Railway Network).For the latter,a methodology to decrease the computational cost of moving loads analysis is introduced.Results show that some theoretical load models constructed within the stipulated limits of the norm can lead to effects not covered by the HSLM.This is especially noted in conventional trains,where there is a relation with larger distances between centres of adjacent vehicle bogies.

Influence of pier height on the safety of trains running on high-speed railway bridges during earthquakes

Sudden earthquakes pose a threat to the running safety of trains on high-speed railway bridges,and the stiffness of piers is one of the factors affecting the dynamic response of train-track-bridge system.In this paper,a experiment of a train running on a high-speed railway bridge is performed based on a dynamic experiment system,and the corresponding numerical model is established.The reliability of the numerical model is verified by experiments.Then,the experiment and numerical data are analyzed to reveal the pier height effects on the running safety of trains on bridges.The results show that when the pier height changes,the frequency of the bridge below the 30 m pier height changes greater;the increase of pier height causes the transverse fundamental frequency of the bridge close to that of the train,and the shaking angle and lateral displacement of the train are the largest for bridge with 50 m pier,which increases the risk of derailment;with the pier height increases from 8 m to 50 m,the derailment coefficient obtained by numerical simulations increases by 75% on average,and the spectral intensity obtained by experiments increases by 120% on average,two indicators exhibit logarithmic variation.

Field survey and analysis on near-fault severely damaged high-speed railway bridge in 2022 M6.9 Menyuan earthquake

The 2022 M6.9 Menyuan earthquake caused severe damage to a high-speed railway bridge,which was designed for high-speed trains running at speeds of above 250 km/h and is located right next to the fault.Bridges of this type have been widely used for rapidly constructing the high-speed railway network,but few bridges have been tested by near-fault devastating earthquakes.The potential severe impact of the earthquake on the high-speed railway is not only the safety of the infrastructure,trains and passengers,but also economic loss due to interrupted railway use.Therefore,a field survey was carried out immediately after the earthquake to collect time-sensitive data.The damage to the bridge was carefully investigated,and quantitative analyses were conducted to better understand the mechanism of the bridge failure.It was found that seismic action perpendicular to the bridge’s longitudinal direction caused severe damage to the girders and rails,while none of the piers showed obvious deformation or cracking.The maximum values of transverse displacement,out-of-plane rotation and twisting angle of girders reached 212.6 cm,3.1 degrees and 19.9 degrees,respectively,causing severe damage to the bearing supports and anti-seismic retaining blocks.These observations provide a basis for improving the seismic design of high-speed railway bridges located in near-fault areas.

Reflection on methodology of the correlation between electromagnetic interference and safety in high-speed railway

Purpose – In the continuous development of high-speed railways, ensuring the safety of the operation controlsystem is crucial. Electromagnetic interference (EMI) faults in signaling equipment may cause transportationinterruptions, delays and even threaten the safety of train operations. Exploring the impact of disturbances onsignaling equipment and establishing evaluation methods for the correlation between EMI and safety isurgently needed.Design/methodology/approach – This paper elaborates on the necessity and significance of studying theimpact of EMI as an unavoidable and widespread risk factor in the external environment of high-speed railwayoperations and continuous development. The current status of research methods and achievements from theperspectives of standard systems, reliability analysis and safety assessment are examined layer by layer.Additionally, it provides prospects for innovative ideas for exploring the quantitative correlation between EMIand signaling safety.Findings – Despite certain innovative achievements in both domestic and international standard systems andrelated research for ensuring and evaluating railway signaling safety, there’s a lack of quantitative and strategic research on the degradation of safety performance in signaling equipment due to EMI. A quantitativecorrelation between EMI and safety has yet to be established. On this basis, this paper proposes considerationsfor research methods pertaining to the correlation between EMI and safety.Originality/value – This paper overviews a series of methods and outcomes derived from domestic andinternational studies regarding railway signaling safety, encompassing standard systems, reliability analysisand safety assessment. Recognizing the necessity for quantitatively describing and predicting the impact ofEMI on high-speed railway signaling safety, an innovative approach using risk assessment techniques as abridge to establish the correlation between EMI and signaling safety is proposed.

Risk assessment of high-speed railway CTC system based on improved game theory and cloud model

Purpose-In order to solve the problem of inaccurate calculation of index weights,subjectivity and uncertainty of index assessment in the risk assessment process,this study aims to propose a scientific and reasonable centralized traffic control(CTC)system risk assessment method.Design/methodologylapproach-First,system-theoretic process analysis(STPA)is used to conduct risk analysis on the CTC system and constructs risk assessment indexes based on this analysis.Then,to enhance the accuracy of weight calculation,the fuzzy analytical hierarchy process(FAHP),fuzzy decision-making trial and evaluation laboratory(FDEMATEL)and entropy weight method are employed to calculate the subjective weight,relative weight and objective weight of each index.These three types of weights are combined using game theory to obtain the combined weight for each index.To reduce subjectivity and uncertainty in the assessment process,the backward cloud generator method is utilized to obtain the numerical character(NC)of the cloud model for each index.The NCs of the indexes are then weighted to derive the comprehensive cloud for risk assessment of the CTC system.This cloud model is used to obtain the CTC system's comprehensive risk assessment.The model's similarity measurement method gauges the likeness between the comprehensive risk assessment cloud and the risk standard cloud.Finally,this process yields the risk assessment results for the CTC system.Findings-The cloud model can handle the subjectivity and fuzziness in the risk assessment process well.The cloud model-based risk assessment method was applied to the CTC system risk assessment of a railway group and achieved good results.Originality/value-This study provides a cloud model-based method for risk assessment of CTC systems,which accurately calculates the weight of risk indexes and uses cloud models to reduce uncertainty and subjectivity in the assessment,achieving effective risk assessment of CTC systems.It can provide a reference and theoretical basis for risk management of the CTC system.

A review of artificial intelligence applications in high-speed railway systems

In recent years,the global surge of High-speed Railway(HSR)revolutionized ground transportation,providing secure,comfortable,and punctual services.The next-gen HSR,fueled by emerging services like video surveillance,emergency communication,and real-time scheduling,demands advanced capabilities in real-time perception,automated driving,and digitized services,which accelerate the integration and application of Artificial Intelligence(AI)in the HSR system.This paper first provides a brief overview of AI,covering its origin,evolution,and breakthrough applications.A comprehensive review is then given regarding the most advanced AI technologies and applications in three macro application domains of the HSR system:mechanical manufacturing and electrical control,communication and signal control,and transportation management.The literature is categorized and compared across nine application directions labeled as intelligent manufacturing of trains and key components,forecast of railroad maintenance,optimization of energy consumption in railroads and trains,communication security,communication dependability,channel modeling and estimation,passenger scheduling,traffic flow forecasting,high-speed railway smart platform.Finally,challenges associated with the application of AI are discussed,offering insights for future research directions.

Influence of span-to-depth ratio on dynamic response of vehicle-turnoutbridge system in high-speed railway

For high-speed railways,the smoothness of the railway line significantly affects the operational speed of trains.When the train passes through the turnout on a long-span bridge,the wheel-rail impacts caused by the turnout structure irregularities,and the instability arising from the bridge's flexural deformation lead to a strong coupling effect in the vehicle-turnout-bridge system.This significantly affects both ride comfort and operational safety.For addressing this issue,the present study considered a long-span continuous rigid-frame bridge as an example and established a train-turnout-bridge coupled dynamic model of high-speed railway.Utilizing a selfdeveloped dynamic simulation program,the study analysed the dynamic response characteristics when the train passes through the turnouts on the bridge.It also investigated the influence of different span-to-depth ratios of the bridge on the vehicle dynamic response when the train passes through the main line and branch line of turnouts and then proposed a span-to-depth ratio limit value for a long-span continuous rigid-frame bridge.The research findings suggest that the changes in the span-to-depth ratio have a relatively minor impact on the train’s operational performance but significantly affect the dynamic characteristics of the bridge structure.Based on the findings and a comprehensive assessment of safety indicators,it is advisable to establish a span-to-depth ratio limit of 1/4500 for a long-span continuous rigid-frame bridge.

High-speed railway track components inspection framework based on YOLOv8 with high-performance model deployment

Railway inspection poses significant challenges due to the extensive use of various components in vast railway networks,especially in the case of high-speed railways.These networks demand high maintenance but offer only limited inspection windows.In response,this study focuses on developing a high-performance rail inspection system tailored for high-speed railways and railroads with constrained inspection timeframes.This system leverages the latest artificial intelligence advancements,incorporating YOLOv8 for detection.Our research introduces an efficient model inference pipeline based on a producer-consumer model,effectively utilizing parallel processing and concurrent computing to enhance performance.The deployment of this pipeline,implemented using C++,TensorRT,float16 quantization,and oneTBB,represents a significant departure from traditional sequential processing methods.The results are remarkable,showcasing a substantial increase in processing speed:from 38.93 Frames Per Second(FPS)to 281.06 FPS on a desktop system equipped with an Nvidia RTX A6000 GPU and from 19.50 FPS to 200.26 FPS on the Nvidia Jetson AGX Orin edge computing platform.This proposed framework has the potential to meet the real-time inspection requirements of high-speed railways.

Study on the Influence of Lanzhou-Urumqi High-Speed Railway on Regional Accessibility and Economic Development

The Lanzhou-Urumqi high-speed railway is an important part of the railway network connecting Gansu,Qinghai,and Xinjiang,and it is of far-reaching significance in facilitating China’s western development.An accessibility model and a double difference model were built to analyze the impact of the Lanzhou-Urumqi high-speed railway on regional accessibility and economic development of the areas along the line before(2012-2014)and after(2017-2019)its opening.The results show that the regional accessibility remains unchanged before and after the operation of this railway line.However,there is a spatial difference in improvement,that of central cities being better.The opening of the high-speed railway is conducive to driving the overall economic development of the region and promoting the comprehensive and coordinated development of regional economies.

Transformer-Based Macroscopic Regulation for High-Speed Railway Timetable Rescheduling

Unexpected delays in train operations can cause a cascade of negative consequences in a high-speed railway system.In such cases,train timetables need to be rescheduled.However,timely and efficient train timetable rescheduling is still a challenging problem due to its modeling difficulties and low optimization efficiency.This paper presents a Transformer-based macroscopic regulation approach which consists of two stages including Transformer-based modeling and policy-based decisionmaking.Firstly,the relationship between various train schedules and operations is described by creating a macroscopic model with the Transformer,providing the better understanding of overall operation in the high-speed railway system.Then,a policy-based approach is used to solve a continuous decision problem after macro-modeling for fast convergence.Extensive experiments on various delay scenarios are conducted.The results demonstrate the effectiveness of the proposed method in comparison to other popular methods.

System architecture and basic platform for intelligent high-speed railway

Purpose-This paper aims to provide top-level design and basic platform for intelligent application in China high-speed railway.Design/methodology/approach-Based on the analysis for the future development trends of world railway,combined with the actual development needs in China high-speed railway,The definition and scientific connotation of intelligent high-speed railway(IHSR)are given at first,and then the system architecture of IHSR are outlined,including 1 basic platform,3 business sectors,10 business fields,and 18 innovative applications.At last,a basic platform with cloud edge integration for IHSR is designed.Findings-The rationality,feasibility and implementability of the system architecture of IHSR have been verified on and applied to the Beijing-Zhangjiakou high-speed railway,providing important support for the construction and operation of the world’s first IHSR.Originality/value-This paper systematically gives the definition and connotation of the IHSR and put forward the system architecture of IHSR for first time.It will play the most important role in the design,construction and operation of IHSR.

Key technologies and applications of intelligent dispatching command for high-speed railway in China

Purpose–The intelligent Central Traffic Control(CTC)system plays a vital role in establishing an intelligent high-speed railway(HSR)system.As the core of HSR transportation command,the intelligent CTC system is a new HSR dispatching command system that integrates the widely used CTC in China with the practical service requirements of intelligent dispatching.This paper aims to propose key technologies and applications for intelligent dispatching command in HSR in China.Design/methodology/approach–This paper first briefly introduces the functions and configuration of the intelligent CTC system.Some new servers,terminals and interfaces are introduced,which are plan adjustment server/terminal,interface for automatic train operation(ATO),interface for Dynamic Monitoring System of Train Control Equipment(DMS),interface for Power Supervisory Control and Data Acquisition(PSCADA),interface for Disaster Monitoring,etc.Findings–The key technologies applied in the intelligent CTC system include automatic adjustment of train operation plans,safety control of train routes and commands,traffic information data platform,integrated simulation of traffic dispatching and ATO function.These technologies have been applied in the Beijing-Zhangjiakou HSR,which commenced operations at the end of 2019.Implementing these key intelligent functions has improved the train dispatching command capacity,ensured the safe operation of intelligent HSR,reduced the labor intensity of dispatching operators and enhanced the intelligence level of China’s dispatching system.Originality/value–This paper provides further challenges and research directions for the intelligent dispatching command of HSR.To achieve the objectives,new measures need to be conducted,including the development of advanced technologies for intelligent dispatching command,coping with new requirements with the development of China’s railway signaling system,the integration of traffic dispatching and train control and the application of AI and data-driven modeling and methods.

Image-Aided Analysis of Ballast Particle Movement Along a High-Speed Railway

As a core infrastructure of high-speed railways,ballast layers constituted by graded crushed stones feature noteworthy particle movement compared with normal railways,which may cause excessive settlement and have detrimental effects on train operation.However,the movement behavior remains ambiguous due to a lack of effective measurement approaches and analytical methods.In this study,an image-aided technique was developed in a full-scale model test using digital cameras and a colorbased identification approach.A total of 1274 surface ballast particles were manually dyed by discernible colors to serve as tracers in the test.The movements of the surface ballast particles were tracked using the varied pixels displaying tracers in the photos that were intermittently taken during the test in the perpendicular direction.The movement behavior of ballast particles under different combinations of train speeds and axle loads was quantitatively evaluated.The obtained results indicated that the surface ballast particle movements were slight,mainly concentrated near sleepers under low-speed train loads and greatly amplified and extended to the whole surface when the train speed reached 360 km.h-1.Additionally,the development of ballast particle displacement statistically resembled its rotation.Track vibration contributed to the movements of ballast particles,which specifically were driven by vertical acceleration near the track center and horizontal acceleration at the track edge.Furthermore,the development trends of ballast particle movements and track settlement under long-term train loading were similar,and both stabilized at nearly the same time.The track performance,including the vibration characteristics,accumulated settlement,and sleeper support stiffness,was determined to be closely related to the direction and distribution of ballast particle flow,which partly deteriorated under high-speed train loads.

Power supply arm protection scheme of high-speed railway based on wide-area current differential

When fault occurs on cross-coupling autotransformer(AT)power supply traction network,the up-line and down-line feeder circuit breakers in the traction substation trip at the same time without selectivity,which leads to an extended power failure.Based on equivalent circuit and Kirchhoff’s current law,the feeder current characteristic in the substation,AT station and sectioning post when T-R fault,F-R fault,and T-F fault occur are analyzed and their expressions are obtained.When the traction power supply system is equipped with wide-area protection measurement and control system,the feeder protection device in each station collects the feeder currents in other two stations through the wide-area protection channel and a wide-area current differential protection scheme based on the feeder current characteristic is proposed.When a short-circuit fault occurs in the power supply arm,all the feeder protection devices in each station receive the feeder currents with time stamp in other two stations.After data synchronous processing and logic judgment,the fault line of the power supply arm can be identified and isolated quickly.The simulation result based on MATLAB/Simulink shows that the power supply arm protection scheme based on wide-area current differential has good fault discrimination ability under different fault positions,transition resistances,and fault types.The verification of measured data shows that the novel protection scheme will not be affected by the special working conditions of the electrical multiple unit(EMU),and reliability,selectivity,and rapidity of relay protection are all improved.

Earthquake Emergency Response System of High-speed Railway by Least Square Method

This paper studies the Least Square Method to define high-speed railway(HSR) earthquake risk and solve the problem of its emergency response mechanism. Based on the construction of a monitoring system for HSR earthquake emergency response, the technical operational procedures for HSR seismic emergency response are proposed. The quantity, scale, and location of HSR earthquake emergency response mechanism are defined, and the corresponding emergency response system is built. In particular, the earthquake emergency response system can conduct real-time continuous dynamic monitoring of seismic activity along the railway. When earthquake occurs, the intensity of the ground motion is detected by the system. When the earthquake monitoring value reaches the earthquake alarm threshold, it will send an alarm signal to the dispatch center, and the emergency power supply will be forced to cut off. The earthquake emergency response system will continue to monitor the follow-up ground motion acceleration. The system provides the operation scheduling center with a basis for train operation control to resume operation after stopping. The monitoring result of the system reduces the disaster, and the secondary disaster is caused by the earthquake. This paper improves the HSR response mechanism in detecting earthquake disasters. The result improves the ability of HSR to deal with earthquake disasters, and reduces casualties and economic and property loss caused by earthquake disasters.

TCP-LTE/5G Cross-layer performance analysis tool for high mobility data networking and a case study on high-speed railway

Nowadays,high mobility scenarios have become increasingly common.The widespread adoption of High-speed Rail(HSR)in China exemplifies this trend,while more promising use cases,such as vehicle-to-everything,continue to emerge.However,the Internet access provided in high mobility environments stllstruggles to achieve seamless connectivity.The next generation of wireless cellular technology 5 G further poses more requirements on the endto-end evolution to fully utilize its ultra-high band-width,while existing network diagnostic tools focus on above-IP layers or below-IP layers only.We then propose HiMoDiag,which enables flexible online analysis of the network performance in a cross-layer manner,i.e.,from the top(application layer)to the bottom(physical layer).We believe HiMoDiag could greatly simplify the process of pinpointing the deficiencies of the Internet access delivery on HSR,lead to more timely optimization and ultimately help to improve the network performance.

Incompatible thermal deformation of interlayers and corresponding damage mechanism of high-speed railway track structure

In the service period,the instability of ballastless track bed are mostly related to the damage of interlayers which are mainly resulted from the incompatible thermal deformation of interlayers.The temperature field within the ballastless track bed shows significant non-uniformity due to the large difference in the materials of various structure layers,leading to a considerable difference in the force bearing of different structure layers.Unit Ballastless Track Bed(UBTB)is most significantly affected by temperature gradient.The thermal deformation of interlayers within UBTB follows the trend of ellipsoid-shape buckling under the effect of the temperature gradient,resulting in a variation of the contact relationship between structure layers and a significant periodic irregularity on the rail.When the train travels on the periodically irregular rail,the structure layers are locally contacted,and the contact zone moves with the variation of the wheel position.This wheel-followed local contact greatly magnifies the interlayer stress,causes interlayer damage,and leads to a considerable increase in the bending moment of the track slab.Continuous Ballastless Track Bed(CBTB)is most significantly affected by the overall temperature variation,which may cause damage to the joint in CBTB.Under the combined action of the overall temperature rise and the temperature gradient,the interlayer damage continuously expands,resulting in bonding failure between structural layers.The thermal force in the continuous track slabs will cause the up-heave buckling and the sudden large deformation of the track slab,and the loss of constraint boundary of the horizontal stability.For the design of a ballastless track structure,the change of bearing status and structural damage related to the incompatible thermal deformation of interlayers should be considered.

MmWave extra-large-scale MIMO based active user detection and channel estimation for high-speed railway communications

The current High-Speed Railway(HSR)communications increasingly fail to satisfy the massive access services of numerous user equipment brought by the increasing number of people traveling by HSRs.To this end,this paper investigates millimeter-Wave(mmWave)extra-large scale(XL)-MIMO-based massive Internet-of-Things(loT)access in near-field HSR communications,and proposes a block simultaneous orthogonal matching pursuit(B-SOMP)-based Active User Detection(AUD)and Channel Estimation(CE)scheme by exploiting the spatial block sparsity of the XLMIMO-based massive access channels.Specifically,we first model the uplink mmWave XL-MIMO channels,which exhibit the near-field propagation characteristics of electromagnetic signals and the spatial non-stationarity of mmWave XL-MIMO arrays.By exploiting the spatial block sparsity and common frequency-domain sparsity pattern of massive access channels,the joint AUD and CE problem can be then formulated as a Multiple Measurement Vectors Compressive Sensing(MIMV-CS)problem.Based on the designed sensing matrix,a B-SOMP algorithm is proposed to achieve joint AUD and CE.Finally,simulation results show that the proposed solution can obtain a better AUD and CE performance than the conventional CS-based scheme for massive IoT access in near-field HSR communications.

Research on revision of relevant provisions of high-speed railway emergency disposal in the regulations on railway technical management(RRTM)

Purpose–This study aims to improve the rules and regulations system of high-speed rail emergency disposal.Design/methodology/approach–Based on the analysis of the demands,rules and regulations of China concerning on-site high-speed rail emergency disposal,basic principles for revising the regulations on railway technical management(RRTM)are proposed and suggestions and evaluation methods according to the main clauses are put forward.Findings–Basic principles for revising the RRTM are proposed,namely“to meet the actual needs of on-site high-speed railway emergency disposal,standardize the emergency disposal process,improve the efficiency of emergency disposal and keep the consistency between provisions of emergency disposal”.Existing provisions related to emergency disposal efficiency,scenarios,safety and service quality are made up for the deficiencies.To make up for the deficiencies of the existing provisions related to emergency disposal efficiency,improvement of emergency disposal scenarios and guarantee of emergency disposal safety and quality,this paper puts forward suggestions on revising 15 emergency disposal provisions of the RRTM with regard to earthquake monitoring and warning,in-station foreign body invasion warning,air conditioning failure of EMU trains and forced parking of trains in sections.A fuzzy comprehensive evaluation model based on the analytic hierarchy process(AHP)is constructed to evaluate the proposed revision scheme and suggestions,which has been highly recognized by experts.Originality/value–This study implements the goal of high-quality railway development.

Challenges of the Performance Standards of the International Finance Corporation in Financing the African Integrated High-Speed Railway Network and the Way Forward: The Case of Standard Gauge Railway in Tanzania

Financing of the African Integrated High-Speed Railway Network (AIHSRN) through Standard Gauge Railway (SGR) Projects is very expensive. As a result, most of the African countries seek financial supports from the International Financial Institutions (IFIs). However, conditions provided by the IFIs through the Performance Standards (PS) of the International Financial Corporation (IFC) increase cost of the projects and thus, it becomes a burden to most of the African countries. This study aimed to explore the causes of IFC-PS through the SGR Projects that escalate costs and how to address them. The Tanzania SGR Lot 1 Project that covered 205 km from Dar es Salaam to Morogoro was selected as a case study. The methods used for data collection involved literature review, focus group discussions and interviews. The results and findings show a gap between the IFC-PS and the National Laws and Regulations that escalates costs of the projects if funds from the IFIs were to be secured. To bridge the gap, it is recommended that the African countries should engage into negotiations with the IFIs to agree to waive IFC-PS conditions that escalate costs provided they are adequately covered in the national laws and regulations;engagement of locally established national and regional financial institutions;and the responsible government institutions in the African countries should sit together for assessment and review of the IFC-PS against the national laws and regulations.